Determination of single-site absorption spectrum in dye-doped disordered materials by double site-selective spectroscopy

Abstract By a combination of site-selective fluorescence-excitation and persistent spectral hole burning spectroscopies, the single-site absorption spectrum has been determined in dye-doped disordered materials for the first time. It has been found theoretically that the difference between the site-selective excitation spectra before and after hole burning by monochromatic light exactly gives the single-site absorption spectrum at very low temperatures. In the measurement of the excitation spectrum, the intensity of fluorescence from chlorin-doped polystyrene having the same wavelength as the exciting light has been obtained by rejecting the scattered laser light using a time gate with a time-correlated single-photon counting method. Site-selective fluorescence spectra before and after hole burning were also measured to compare their difference with the experimentally determined single-site absorption spectrum.